Skip to content

Serum or Plasma Substance Concentration for a Specific Protein (e.g., Alpha-1 Antitrypsin or similar)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of a particular protein in your blood, often used to check for conditions affecting protein levels or function.

Quick summary

["This test helps diagnose or monitor conditions linked to abnormal protein production or breakdown."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
19200-5
Short code
PSA Smn-sCnc
Synonyms
PSA Smn-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
4
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84153
SNOMED
39392002
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like fatigue, organ damage (such as liver or lung issues), or a family history of protein-related disorders. It can also be part of routine screening or follow-up for certain diseases.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. Avoid smoking or consuming certain medications for the recommended time. Bring any medications you’re currently taking.

What Happens During the Test

A healthcare professional will collect a blood sample from a vein in your arm. You may feel a slight pinch, but it’s usually over quickly. The sample is then sent to a lab for analysis.

What the Results Mean

Results are compared to a general reference range for healthy adults. Low levels may indicate conditions like alpha-1 antitrypsin deficiency, while high levels could suggest inflammation, liver disease, or other metabolic issues. Your provider will discuss findings in the context of your symptoms and medical history.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

How does this test help doctors diagnose conditions?
This test helps identify protein-related disorders by detecting abnormal concentrations. For example, low levels of alpha-1 antitrypsin can signal lung or liver disease, while elevated levels may point to conditions like cirrhosis or chronic inflammation. It’s also used to monitor treatment progress or screen for hereditary disorders.
What are common reasons for abnormal results?
Abnormal results can occur due to genetic factors (e.g., inherited protein deficiencies), chronic illnesses (e.g., liver disease, kidney problems), infections, or medications. Symptoms like jaundice, shortness of breath, or unexplained weight loss may prompt further testing.
Can lifestyle changes affect this test result?
Yes, diet, exercise, smoking, and certain medications can influence protein levels. For instance, fasting may affect some protein measurements, and smoking can lower alpha-1 antitrypsin levels. Always follow your provider’s instructions for test preparation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy